TWI406720B - Method and device for the continuous casting of preliminary steel sections, in particular preliminary i-sections - Google Patents

Abstract

The continuous casting of preliminary double-T steel sections, comprises introducing liquid steel substantially vertically into an open-ended die (1) and supplying partially hardened preliminary section to a strand guide with secondary cooling equipments. The cross section of the cavity of the open-ended die is made up of two flange parts (2,3) and a web part (4) and applied on a liquid strand in the preliminary section over magnet poles of magnetic fields. A 3-phase alternating current is supplied to agitating coils (19) of an agitator over a pole wiring. The continuous casting of preliminary double-T steel sections, comprises introducing liquid steel substantially vertically into an open-ended die (1) and supplying partially hardened preliminary section to a strand guide with secondary cooling equipments. The cross section of the cavity of the open-ended die is made up of two flange parts (2,3) and a web part (4) and applied on a liquid strand in the preliminary section over magnet poles of magnetic fields. A 3-phase alternating current is supplied to agitating coils (19) of an agitator over a pole wiring in dependence of a thickness of the web part, a steel quality and a symmetrical or asymmetrical steel supply with one or two sprue (passage) in such a manner that electromagnetic travelling waves are applied in the liquid strand of the preliminary section with horizontal direction components. The travelling waves are generated in the flange parts with direction components rotating in same- or opposite direction and/or in the web part with linear direction components and/or in the area of the open-ended die and/or in different and adjustable heights in the preliminary section and/or in transition area or area of the web part with direction components rotating in same- or opposite direction. The liquid steel is supplied on the sprue intended symmetrically or asymmetrically in the web part and the distribution of the liquid steel is supported over the cross section of the cavity depending upon casting parameters and/or product parameters by the rotary and/or linear travelling waves. An INDEPENDENT CLAIM is included for a device for continuous casting of preliminary double-T steel sections.

Description

Continuous casting method and device for bismuth steel, especially 預鑄I steel

The present invention relates to a method and apparatus for continuously casting a 預鑄-shaped steel, in particular a 預鑄I-shaped steel, according to the preamble of the first application of the scope of the patent application, and a device for carrying out the method.

Tantalum steel is the initial material used to produce rolled section steel beams of I, H, U and Z cross-section shapes as well as special sheet pile profiles. A method for continuously casting such initial profiles is disclosed, for example, in EP-B-1 419 021. Continuous casting of initial profiles was promoted on an industrial scale in the 1970s and has become increasingly important in recent years due to the general trend towards so-called near-net shape casting.

The initial profile has an I-shaped cross-sectional shape in most cases, and the molten steel is introduced substantially vertically into a so-called "eight-shaped test piece"-like continuous mold having a cavity portion of two flange portions and a web. Part of the composition. An initial section strip having a molten core is then sent from the mold to a strip guide having an auxiliary cooler.

Unlike continuous casting of conventional long products of rectangular or circular cross-section, there are several problems with continuous casting of the initial I-shaped profile, especially in the case of initial profiles with relatively thin web sections, in casting high strength special Steel grade (especially steel with CaSi or Al deoxidized and microalloyed with V, Nb), or in the case of high speed casting. For reasons of space, but for economic reasons, the molten steel is introduced into the mould only through an ingate, which in most cases is asymmetrically located in the transition section between the web section and a flange section. . Therefore, it is particularly difficult to uniformly fill the complex cavity without disturbing turbulence, thereby forming an advantageous initial solidification state while preventing casting defects (bubbles, pinholes) close to the surface. Furthermore, the difficulty lies in obtaining a symmetrical liquid flow inside the strip casing and thus also obtaining a symmetrical temperature distribution, which ultimately leads to a homogeneous solidified structure. It is also problematic to prevent arching and, as a result, core apertures and/or craters during solidification where thin web portions are involved.

A continuous mould for continuous casting of an initial I-section strip is known from JP 08 294746 A. The molten steel is introduced into the two flange portions through two immersion nozzles. In order to prevent surface defects on the initial section strip, it is proposed to arrange a pair of stationary magnetic poles having S or N poles on the outside of the two flanges and on the web portion on the outside of the cavity. Since the stationary magnetic field is being immersed under the nozzle opening, the molten steel emerging from the immersion nozzle will slow down and flow back to the mold wall in a horizontal flow and along here to the liquid surface. The static magnetic field with N and S poles causes a slowing down of the vertical discharge flow from the immersion nozzle and an uncontrollable fold from the vertical flow. This prior art does not involve a controlled reversible traveling magnetic field or flow for forming a controlled flow in the molten crater and a temperature state within the initial section strip crater.

The object of the invention is to recommend such a method mentioned at the outset and a device for carrying out the method, whereby an initial steel profile comprising two flange portions and a web portion can be produced with improved quality, Even if the initial profile comprises a relatively thin web portion and/or a special steel grade is to be cast. A further objective, depending on the size of the initial section strip or the quality of the steel, is the ability to feed symmetric or asymmetric molten steel into the selected mold with one or two open or closed ingates.

According to the present invention, this object is achieved using the method according to the first aspect of the patent application and the use of the device having the feature of claim 8 of the patent application.

The method according to the invention and the optimal development of the device according to the invention constitute the subject matter of the appended claims.

According to the invention, due to the use of electromagnetic induction forces, the molten core of the initial section strip is subjected to a plurality of agitating movements transverse to the direction of casting of the strip in the region of the flange portion and/or the web portion, and due to the agitation Movement, such that molten steel in the initial section strip crater is exchanged between the flange portion and the web portion, and may also clearly and effectively affect the molten steel crater inside the initial section strip casing The flow and temperature conditions, and thereby producing the following effects: - Stabilizing the surface area of the metal by means of turbulence suppression, even in varying process parameters such as casting speed, metal surface position (to prevent non-metals in the surface of the strip) The same is true for inclusions and bubbles; - an advantageous, controlled flow state with a special exchange of molten metal through which the web portion occurs between the two thick chamber regions, even in the case of an asymmetric ingate The same is true, and thereby forming a non-uniform thickness strip casing with a suitable solidified structure, while at the same time preventing shrinkage cavities and/or core porosity; - regardless of the tube cross-section The constrained state within the web portion of the section prevents arching during solidification.

In addition, a variety of different traveling magnetic field combinations within the flange portion and/or the web portion can be selected where the same agitator is used to vary the steel mass or different dimensions of the initial section strip. If the casting system is changed, a traveling magnetic field having components of completely different orientations can also be set in the flange portion and/or the web portion without any structural change of the agitator.

Figure 1 shows in a schematic manner a mould 1 or its cavity cross section, which consists of two flange portions 2, 3 and a web portion 4. Mold 1 is intended for continuous casting of the initial I-profile. The molten steel is introduced into the continuous mold substantially vertically, and a strip surface layer is formed therein, and the initial section strip having the molten core portion is fed therefrom into a strip guide having an auxiliary cooler.

According to the invention, the molten core of the initial section strip is preferably transversely cut in the region of the mould 1 or directly at the exit of the mould 1 by means of a magnetic stirrer 10 and using electromagnetic induction forces generated by three-phase currents. The strip casting direction achieves agitating motion, and the molten steel in the initial section strip crater is thereby exchanged between the flange portions 2, 3 and the web portion 4.

The agitator 10 appearing in Figure 1 comprises an annular closing yoke 11 which surrounds a certain vertical area of the mould 1 and has six poles in the form of pole pieces 12 to 17, and each pole is surrounded by an electromagnetic coil 19. . The pole pieces 12 to 17 are unevenly distributed at the circumference of the yoke 11 such that the pole pieces 12, 13 each face the flange portions 2, 3, and the two pole pieces 14, 15; 16, 17 are each directed from both sides Web section 4. The agitator 10, or the rotary agitator of this example, operates according to the principle of a six-pole asynchronous machine, in which case a traveling magnetic field can be generated by means of three-phase current. In this respect a plurality of magnetic poles must be correctly interconnected in order to produce a linear or linear or rotational or linear or rotational flow.

In the embodiment shown in Fig. 2 the mould 1 is also surrounded by a magnetic stirrer 20 having an annular closing yoke 21 in a certain and preferably adjustable vertical region, which is also unevenly distributed at the circumference of the yoke. Six pole pieces 22 to 27 are distinguished, with the difference that all six pole pieces 22 to 27 are generally oriented by the web portion 4 to create a plurality of linear flows.

According to Figures 3 to 6, a magnetic stirrer 30 is associated with the mould 1 in each case, the stirrer comprising a closed yoke 31 surrounding the mould 1 and formed as a rectangular frame, and associated with its length side Three respective pole pieces 34, 35, 36 and 37, 38, 39 are distributed over the width of the mould, the narrow sides being provided with respective central pole pieces 32, 33 facing forward towards the flange portions 2, 3. As described below, the agitator 30 can function both as a rotary agitator and as a linear agitator, depending on the magnetic pole interconnection, ie the pole piece is intended to be excited by the interconnection and has its phase sequence (see phase mark U) , V, W; U', V', W'). Four different working possibilities are shown in accordance with Figures 3 to 6, wherein a total of eight of the eight pole pieces 32 to 39 are energized according to their respective circumstances.

Where the pole interconnections are indicated in Figure 3, the center pole pieces 32, 33 in the flange region are broken, while the pole pieces 34, 35, 36 on one long side of the yoke 31 are opposite in length. The pole pieces 37, 38, 39 on the side are phase-shifted, resulting in a straight flow in the opposite direction of the web portion 4 (2 x 3-pole linear operation, in opposite directions). This pole interconnect is preferably used for the symmetric arrangement of the gates 45, 46 within the flange portions 2, 3.

Figure 4 similarly shows an interconnection for a straight line operation (the center pole pieces 32, 33 in the flange region are broken) with phase sequences U, V, W on the two long sides, resulting in a web portion 4 in the same direction of flow (2 × 3 - magnetic pole straight work, in the same direction). Such a pole interconnect is preferably used in the case of an asymmetrical arrangement of the gate 47 in the flange portion 2 or 3.

Where the pole interconnections are indicated in Figure 5, the center pole pieces 32, 33 in the flange region are energized, but the three pole pieces 34, 35, 36 associated with the two long sides; 37, 38, 39 The center pole piece in the middle is disconnected (the pole pieces 35, 38 are not energized). Therefore, a plurality of rotating magnetic fields (2 × 3 - magnetic pole straight work) are generated in the flange region. Due to the phase distribution indicated by the pole pieces 37, 32, 34 and 36, 33, 39, the direction of rotation of the rotating magnetic field in the two flange portions 2, 3 is the same, which also results in a flow in the web portion 4. However, this is less efficient than the straight line operation according to Fig. 3. This pole interconnect is preferably used in the case of a symmetrically disposed gate 48 in the web portion 4.

In consideration of the interconnection of the pole pieces 34, 32, 37 and 36, 33, 39 according to Fig. 6, the agitator 30 can also be used to generate a plurality of rotating magnetic fields having a relative rotational direction in the flange portions 2, 3. This pole interconnect is preferably used in the case of two symmetrically disposed gates 45, 46 in the flange portions 2, 3.

Figures 7 and 8 show a variant in which two electromagnetic stirrers 40, 40' or two are separated from one another in the width direction of the mould 1 and have three respective pole pieces 42, 43, 44; 42', 43', 44' The yokes 41, 41' are associated with the mold 1 at the periphery of the latter, and each yoke 41, 41' is provided with a central pole piece 42, 42' and two pole pieces 43, 44; 43', 44' The pole pieces 42, 42' are directed forward towards the respective flange portions 2, 3, while the pole pieces 43, 44; 43', 44' are directed directly from the sides to the flange portions 2, 3. By means of the two agitators 40, 40', it is also possible to cause a 2x3-pole rotation operation, or to generate a plurality of identical rotational directions (Fig. 7) or relative rotational directions in the flange portions 2, 3 ( Figure 8) The rotating magnetic field. 48 indicates a symmetrical ingate.

Actually, the two agitators 40, 40' or the yokes 41, 41' which are separated from each other in the width direction of the mold 1 can be achieved as in the case of the agitator 30 provided with the closing yoke 31 and connected as shown in Fig. 5 or 6. The same effect. However, this solution also offers several additional advantages. The electromagnetic stirrer can be constructed with two separate agitators or semi-agitators which can be removed from the outside or mounted on the mould 1 with relative ease. Designers can gain room through this free section. In particular, this solution allows the two agitators 40, 40' to be arranged in a vertical staggered arrangement as shown in Figure 9, in which case the agitators are arranged opposite each other and/or vertically relative to the height of the mould. 40, 40' is best adjusted as needed. 49 indicates an asymmetric ingate.

A similar advantage can also be provided by means of the solution according to Figures 10 to 12, in which two electromagnetic stirrers 50, 50' (Figures 10 and 13) or 60, 60' (Figures 11 and 12) can also be placed with the mould 1 The latter is associated at the periphery, but these agitators include yokes 51, 51' which are separated from each other in the thickness direction of the mold 1, rather than in the width direction thereof. Each yoke is provided with three pole pieces 52, 53, 54; 52', 53', 54' or 62, 63, 64; 62', 63', 64' in each case.

In the embodiment according to Fig. 10, three pole pieces 52, 53, 54; 52', 53', 54' are distributed over the entire width of the initial profile in each case, and two of them (pole shoe 52) , 54; 52', 54') are directed toward the sides of the flange portions 2, 3, and the center pole pieces 53, 53' project toward the web portion 4.

In the embodiment according to Figures 11 and 12, all three pole shoes 62, 63, 64; 62', 63', 64' of the respective agitator 60, 60' are only distributed within the web and towards the web portion 4 stretched out. Two symmetrical ingates are indicated by 45, 46.

The agitators 50, 50' and 60, 60' each function as a linear agitator, in which case the flow in the opposite direction can be generated in the web portion 4 (Figs. 10 and 11) or in the same direction (Fig. 12). . This setting is determined based on the casting and/or product parameters.

Finally, Fig. 14 shows an electromagnetic stirrer 70 having an octopole structure which is constructed in a similar manner to the agitator 30 of Figs. 3 to 6 (which is associated with a yoke 71 formed as a rectangular frame with three sides on the length side thereof Corresponding pole pieces 74, 75, 76; 77, 78, 79 are distributed over the width of the mould, while the narrow sides are provided with respective central pole pieces 72, 73 facing forward towards the flange portions 2, 3. However, In this embodiment, instead of selecting between two of the eight poles, the rotary and linear operations are selected, but a 1 x 6-pole linear agitator (pole boots 74, 75, 76; 77, 78, 79) generating a plurality of linear magnetic fields in the web portion 4 and simultaneously generating the same in the flange portions 2, 3 by means of a 2 x 3-pole rotary agitator (pole shoes 74, 72, 77 and 76, 73, 79) Multiple rotating magnetic fields.

Figure 15 shows an electrical wiring diagram of an agitator 70 having such an eight-pole structure or such an eight-pole system in which a plurality of linear magnetic fields are generated by means of a 1 x 6-pole linear stirrer, while a plurality of rotating magnetic fields utilize these 2 x 3-pole rotating mixer to produce. This electromagnetic stirrer 70 is powered by electrical circuits 81, 82, for example, 50 Hz three-phase currents, which are led to frequency converters 83, 84 in each case. These frequency converters 83, 84 are connected to a converter control unit 85, and each phase is set at a predetermined frequency.

The function of the control device 85 is to adjust the mutual frequencies of the two converters in order to synchronize the agitation movements occurring in the web and in the transition region reaching the two flange portions on the one hand. The control device is also used to prevent yaw from occurring when the two agitators are at slightly different frequencies. This yaw may cause one or the other magnetic pole to be at full load at the same time, which results in a highly uneven circuit load.

The respective phases U, V, W of one converter 84 and the phases U ₁ , V ₁ , W ₁ of the other converter 83 are transmitted from these frequency converters 83, 84 to the winding pole shoes 74, 75, 76; 78, 79 on multiple coils. The phases U, V, W lead to the coils 77', 78', 79' at the web portion pole pieces 77, 78, 79 and are further guided to the coils of the pole pieces 76, 75, 74 arranged symmetrically with respect to the former 76', 75', 74', and the connecting wires are sent diagonally from the coils 77', 79' to the coils 76', 74' (series connected). The wires are sent from these coils to the star connection point 87. The same connection method is applied to the phases U ₁ , V ₁ , W ₁ , but will not be described in detail. In the case of a straight line operation, the phase W _{1 is} sent to the coil 72' and then sent to the opposite coil 73' and further to a star connection.

As already mentioned, it is therefore possible to utilize electromagnetic stirrers 10; 20; 30; 40, 40'; 50, 50'; 60, 60'; 70 and to utilize in the flange portion and/or the web portion The electromagnetic induction force causes the initial section strip molten core to achieve agitating motion transverse to the strip casting direction, and thereby the molten steel in the initial section strip crater is in the flange portion and the web Exchange between the parts. The result is a clear and effective influence on the flow and temperature conditions in the molten steel crater inside the initial section strip casing, and thereby producing the following effects: - stabilizing the metal surface area by suppressing turbulence, even This is also true when varying process parameters such as casting speed, metal surface position (to prevent non-metallic inclusions and bubbles in the surface of the strip); - advantageous, controlled flow conditions with specialized molten metal exchange, said exchange This occurs between the two thickened cavity regions through the web portion, even in the case of an asymmetrical inner gate, and thereby forms a non-uniform thickness strip casing with a suitable solidified structure, while preventing shrinkage The holes and/or the core are constricted; - regardless of the constrained state within the web portion of the cross-section of the cavity, arching is prevented during solidification.

As a result of freely selecting the magnetic pole interconnections with the respective phases of the three-phase current, a plurality of different directional components can be produced without any structural changes to the agitator, and thereby depending on the pouring parameters, for example, regardless of the number of gates The ingate system, open or closed injection, casting speed, casting temperature, steel composition, and the like create a plurality of different flows within the initial section strip molten crater. It is also possible to use the same agitation means for a plurality of dies having different product parameters, such as initial section dimensions, and at the same time to change the pole interconnections so that a rotational traveling magnetic field can be generated in the flange portion according to the product parameters and/or A linear traveling magnetic field is generated within the web portion to provide a clear variety of flows within the molten crater.

A variety of tubular dies are shown schematically in the drawings. However, it is also possible to replace the tubular mould with the method according to the invention or with the device according to the invention, thereby manipulating all mould structures suitable for a variety of initial sections, such as ingot moulds or plate moulds and the like.

1‧‧‧Mold

2,3‧‧‧Flange section

4‧‧‧ web section

10,20,30,40,40’,50,50’,60,60’,70‧‧‧Agitator

11,21,31,41,41’,51,51’‧‧ yoke

12~17,22~27,32~39,41~44,41’~44’,52~54,52’~54’,62~64,62’~64’,72~79‧‧‧ pole boots

19,72’~79’‧‧‧ coil

45, 46, 48, 49‧‧ ‧ gate

81,82‧‧‧Wire

83,84‧‧‧ frequency converter

85‧‧‧Control device

87. . . Junction point

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in detail with reference to the accompanying drawings, in which: FIG. 1 is a cross section of a mold having a first embodiment of a magnetic stirrer; and FIG. 2 is a cross-section of a mold having a second embodiment of a magnetic stirrer Figure 3-6 is a third embodiment of a magnetic stirrer associated with a mold and having a plurality of different pole piece connections; Figure 7+8 is a mold with two agitators, the agitator having multiple a different pole piece connector; Figure 9 is a side view of the mold with two agitators; Figure 10 is a side view of the mold with two other embodiment agitators; Figure 11 + 12 is a mixture with two other embodiments Side view of the mold, the agitator having a plurality of different pole piece connections; Figure 13 is a side view of the agitator of Figure 10; Figure 14 is a further embodiment of a mold having a magnetic agitator; and Figure 15 is for Figure 14 is an electrical wiring diagram of the agitator.

1. . . Mold

2,3. . . Flange part

4. . . Web section

10. . . Blender

11. . . Yoke

12~17. . . Polar boots

19. . . Coil

Claims (16)

A method for continuously casting a 預鑄-shaped steel, in particular a 預鑄I-shaped steel, wherein the molten steel is introduced substantially vertically into a cavity of a continuous mold (1) having a cross-section of two flanges a portion (2, 3) and a web portion (4), and applying a plurality of magnetic fields to a molten crater in the initial section strip through a plurality of magnetic poles, after which the initial solidification is partially performed The section strip is fed to a strip guiding device having a plurality of auxiliary coolers, characterized in that a plurality of three-phase alternating current and a plurality of agitator coils (19) are generated in the initial section strip melting crater Electromagnetic traveling magnetic fields having a directional component that causes a plurality of transverse directions to flow in the direction of travel of the strip, and the three-phase alternating current is supplied to the agitator coils (19) via a magnetic pole interconnect such that the melting A plurality of traveling magnetic fields having a component of a rotational direction are generated in the flange portions (2, 3) inside the crater and/or a plurality of traveling magnetic fields having linear component components are generated in the web portion (4). The method of claim 1, wherein the traveling magnetic field is generated within the range of the continuous mold (1). The method of claim 1 or 2, wherein the traveling magnetic fields are generated at a plurality of different adjustable heights within the initial section strip. The method of claim 1, wherein the traveling magnetic field having a plurality of directional components rotating in the same direction or in opposite directions is generated in the molten crater inside the two flange portions (2, 3) In particular, it is generated in the transition region that reaches the web portion (4). The method of claim 1, wherein a traveling magnetic field having a plurality of linear direction components in the same direction or in opposite directions is generated in the molten crater inside the web portion (4) region. The method of claim 1, wherein the molten steel is fed into the cavity through a preferably symmetrically disposed ingate (48) in the web portion (4), and the molten steel is in the cavity The distribution within the cross-sectional range is aided by a plurality of rotational and/or linear traveling magnetic fields depending on the casting parameters and/or product parameters. The method of claim 1, wherein the molten steel is fed into the cavity through an asymmetrically disposed ingate (49) in a flange portion (2, 3), and the molten steel is in the type The distribution within the cross-section of the cavity is aided by a plurality of rotational and/or linear traveling magnetic fields depending on the casting parameters and/or product parameters. A device for carrying out the method of claim 1, wherein the plurality of magnetic poles are disposed outside the mold cavity of the 預鑄I-shaped steel, the cavity cross section being composed of two flange portions (2, 3) And a web portion (4), and a strip guiding device with an auxiliary cooler is disposed downstream of the mold, characterized in that the magnetic poles are associated with an electromagnetic stirring device for three-phase current to generate a plurality of traveling magnetic fields having a plurality of directional components transverse to the direction of travel of the strip, and the stirring device is provided with a magnetic pole interconnect to distribute the plurality of phases of the three-phase current to form a pole piece (12, 13, Each of the magnetic poles of 14,15,16,17) and capable of having a plurality of rotational direction components in the flange portions (2, 3) and/or a plurality of linear directions in the web portion (4) The component connects a plurality of electromagnetic traveling magnetic fields. The device of claim 8, wherein one or more of the agitating devices are provided with six or more pole pieces (12, 13, 14, 15, 16; 22, 23, 24, 25, 26, 27) And the connection of the three-phase electrical phase to each of the pole pieces (12, 13, 14, 15, 16; 22, 23, 24, 25, 26, 27) can be freely selected according to the casting and/or product parameters, In order to set a plurality of the directional components and the athletic ability of the traveling magnetic fields. A device according to claim 8 or 9, wherein the pole pieces (12, 13, 14, 15, 16; 22, 23, 24, 25, 26, 27) are arranged at a common yoke. The device of claim 8, wherein the agitator (10; 20) comprises an annular closing yoke (11; 21) surrounding the continuous die (1) and is unevenly arranged around the yoke Six pole pieces (12, 13, 14, 15, 16, 17; 22, 23, 24, 25, 26, 27) so that they face the flange portions (2, 3) and the web portion ( 4) Or just toward the web portion (4). The device of claim 8, wherein the agitator (30; 70) comprises an annular closing yoke (31; 71) surrounding the continuous die (1) and is formed as a rectangular frame having a length Three separate pole pieces (34, 35, 36, 37, 38, 39; 74, 75, 76, 77, 78, 79) distributed over the width of the mold are provided on the side, and the narrow sides are provided with a direction The respective center pole pieces (32, 33; 72, 73) that face the flange portions (2, 3). Such as the device of claim 8 of the patent scope, wherein the continuous The molds (1) are separated from each other in the width direction and have two agitators (40, 40') or two yokes (41, 43, 44; 42', 43', 44'). , 41') associated with the continuous mold (1) at the periphery of the latter, wherein each yoke (41, 41') is provided with a central pole piece forward facing the respective flange portions (2, 3) (42 , 42') and two pole pieces (43, 44; 43', 44') from the sides toward the flange portion (2, 3). The device of claim 8, wherein the two continuous shoe (1) are separated from each other and have three separate pole pieces (52, 53, 54; 52', 53', 54') A stirrer (50, 50') or two yokes (51, 51') are associated with the continuous mold (1) at the periphery of the latter, wherein the three pole pieces are distributed in each case over the width of the mold And two of them face the flange portions (2, 3) at the side, and the center pole pieces (53, 53') face the web portion (4). A device according to claim 8, wherein the two separate pole pieces (62, 63, 64; 62', 63', 64') are separated from each other in the thickness direction of the continuous mold (1). A stirrer (60, 60') or two yokes are associated with the continuous die (1) at the periphery of the latter, wherein the three pole pieces are distributed over the width of the web portion. A device according to any one of claims 11 to 13, wherein the agitator (40, 40'; 50, 50'; 60, 60') or the yoke (41, 41'; 51, 51' They are arranged in a vertical staggered manner within the mold area, and their vertical alignment with respect to the height of the mold can be adjusted independently of each other.